Modern vehicles typically have one or more diagnostic systems, generally having separate computer control modules to control various functions of the vehicle. Some examples include powertrain control module (PCM), engine control module (ECM), a transmission control module (TCM), anti-locking brake system (ABS), and an air bag control module. The vehicle diagnostic systems often have self-diagnostic capability to detect and alert the driver of problems the vehicle may be encountering. When a problem is found, a diagnostic trouble code or DTC, is set within the computer's memory. DTCs are as general or as specific as the manufacturer desires.
To retrieve and decipher DTCs, an auto repair technician needs a diagnostic tool, such as a scan tool. The scan tool must, therefore, be connected to the vehicle's computer bus system via a data link connector (DLC) to access and retrieve the DTCs. Scan tools are testing devices that interface with vehicle diagnostic systems to retrieve information from the various control modules. The scan tools are equipped to communicate in various communication protocols such as Controller Area Network (CAN), J1850 VPM and PWM, ISO 9141, Keyword 2000 and others. These communications protocols may be specific to the various automobile manufacturers. The scan tool will help the technician to diagnose and repair the vehicle based on the information the tool retrieves from it.
Unfortunately, the vehicle's diagnostic systems are not designed to know certain conditions of the vehicle when an issue arises. For example, a customer may complain that his vehicle intermittently loses power when climbing an inclined road, such as a hill or a mountain. However, the vehicle's diagnostic system can not provide the information as to the location and altitude when this intermittent issue occurs. The mechanic can use a conventional scan tool to help him diagnose the issue but can not verify the repair has been completed properly as he does not know at exactly what altitude and location the issue occurs.
Accordingly, it is desirable to provide a method and apparatus that allow a diagnostic tool to perform both diagnostic and ascertain the altitude and location when a problem occurs.